The present invention relates to an airbag apparatus that, when the impact of a crash or the like is applied to the front section of a vehicle, deploys and inflates an airbag at a position forward of the occupant seated on a vehicle seat and thus protects the occupant.
An airbag apparatus is effective as a device for protecting an occupant of a vehicle from the impact of a crash or the like that is applied to the front section of the vehicle.
For example, an airbag apparatus described in Japanese Laid-Open Patent Publication No. 2017-109684 includes an airbag and an inflator, which supplies inflation gas to the airbag in response to an impact applied to the front section of a vehicle. The airbag is deployed and inflated by the inflation gas at a position forward of a vehicle seat. The airbag includes a main bag member and an auxiliary bag member, which has a smaller volume than the main bag member. The main bag member is attached to the steering wheel together with the inflator. The auxiliary bag member is arranged on the rear side of the main bag member and communicates with the main bag member through a communicating portion.
When an impact is applied to the front section of the vehicle from forward or diagonally forward, the body of the occupant acts to lean to the side from which the impact has been applied due to the inertia. Meanwhile, in the airbag apparatus, the inflation gas is supplied from the inflator to the main bag member in response to the impact, which deploys and inflates the main bag member rearward. Some of the inflation gas that has been supplied to the main bag member passes through the communicating portion and is supplied to the auxiliary bag member. This deploys and inflates the auxiliary bag member rearward.
In the initial stage of deployment and inflation of the airbag, the auxiliary bag member, which has a smaller volume than the main bag member, projects rearward from the main bag member. The head of the occupant thus comes into contact with the auxiliary bag member at an earlier time than the thorax of the occupant comes into contact with the main bag member. Through such contact, the auxiliary bag member receives a load from the head and produces a reactive force that acts rearward, thus restraining and protecting the head. On the other hand, the main bag member receives load either indirectly through the auxiliary bag member or directly from the thorax. By receiving a load in these manners, the main bag member also produces a reactive force that acts rearward, thus restraining and protecting the thorax. As a result, unlike an airbag that lacks an auxiliary bag member and is configured simply by a main bag member, intense pressing of the thorax by the airbag at an earlier time than that of the head is avoided.
However, in the airbag apparatus described in the aforementioned document, arranging the communicating portion decreases the tensile force of the main bag member. This correspondingly decreases the reactive force produced by the main bag member, which receives load through the auxiliary bag member. The main bag member is thus deformed in a manner crushing forward after the auxiliary bag member is deformed. There is thus room for improvement in the protection of the head by the main bag member after deformation of the auxiliary bag member.